Engine systems, including naturally aspirated engines and boosted engines, utilize exhaust gas recirculation (EGR), where a portion of exhaust gases is recirculated into the intake, to reduce emission from the engine and/or improve fuel economy. In boosted engine systems that utilize compressors in the intake system to provide boosted air charge, the EGR can be delivered in a “high pressure” (HP) loop, where the EGR gases are taken before the turbine and injected after the compressor, or a “low pressure” (LP) loops, where the EGR gases are taken after the turbine and injected before the compressor. The engine systems with EGR include an EGR port in the intake for admitting the EGR gases. The intake housing typically includes a mounting surface for locating the EGR port and installing an EGR tube assembly onto the intake housing.
An example intake housing configuration is shown by Murphy in U.S. Pat. No. 6,874,487. Therein, the intake housing includes an extending boss for receiving an EGR tube assembly and the boss further includes boss extensions. An attachment portion of the EGR tube assembly includes a pair of tabs that are aligned with the boss extensions, and the EGR tube is coupled with the intake housing via fasteners inserted through openings in the tabs and boss extensions.
However, the inventors herein have recognized potential issues with such systems. As one example, during installation of the EGR tube assembly into the intake, the EGR tube assembly may be mis-aligned with the intake housing and coupled without detecting and correcting the mis-alignment. As a result, the EGR tube assembly may be improperly coupled without establishing a tight seal between the EGR tube assembly and the intake housing. Consequently, when EGR gases are delivered from the EGR tube into the intake manifold, leakages can occur. As a result, the assembled intake and EGR tube unit may not pass development and/or end of the line testing, which may lead to delay in delivering the final product. In some examples, the improper assembling may establish a temporary seal and thus, may not be detected during testing and development. However, during subsequent vehicle operation, the temporary seal may not hold, resulting in leakage of gases, and consequently, vehicle performance and emission degradation issues. Furthermore, in some cases, the positioning of the EGR tube assembly may be improper. For example, the EGR tube assembly may be rotated 180 degrees with respect to the correct position. An intake system such as Murphy's does not provide any indication for the incorrect direction of the EGR tube assembly. As a result, the EGR tube may be incorrectly installed, which renders the assembled product unfit for assembly with the engine. This leads to manufacturing delays.
In one example, the issues described above may be addressed by an intake system for an engine, comprising: an intake plenum enclosed by an intake plenum housing; and an exhaust gas recirculation (EGR) port for admitting exhaust gases recirculated by an EGR system into the intake plenum; wherein the EGR port is enclosed by an EGR port housing including a central boss, one or more housing extensions, and one or more alignment tabs, each alignment tab positioned on one side of each housing extension.
In this way, by providing one or more alignment tabs on the EGR port housing, an EGR assembly may be aligned more accurately with the intake housing during the assembly process. Further, the one or more alignment tabs are configured such that the tabs permit coupling of the EGR assembly with the intake only if the EGR assembly is correctly aligned with the EGR port housing on the intake, thereby preventing fastening of the EGR assembly with the intake if mis-aligned.
As one example, an EGR port for delivering EGR gases to the intake is enclosed by an EGR port housing. During an assembly process, an EGR tube assembly is aligned with the EGR port housing via one or more alignment tabs on the EGR port housing and coupled to form an intake-EGR tube unit. Specifically, the EGR port housing includes a central boss for receiving an EGR tube portion of the EGR tube assembly. Further, the EGR port housing includes housing extensions on opposite sides of the central boss. Each housing extension includes an opening for receiving a fastener. Furthermore, the EGR port housing includes one or more alignment tabs, each alignment tab corresponding to each housing extension on one side of the housing extension for guiding and aligning fastener holes on a flange of the EGR tube assembly with the openings on the housing extensions. In one example, each alignment tab extends below each housing extension, each housing extension positioned on opposite sides of the central boss. Further, each alignment tab includes a step-like protrusion on a front side of the EGR port housing, which provides a mounting and aligning surface for the EGR tube assembly. Specifically, during assembly process, the EGR tube portion of the EGR tube assembly is inserted into the central boss, and the flange of the EGR tube assembly is positioned on the step-like protrusion of the alignment tab, and guided to align the fastener holes on the flange with the openings on the housing extensions. Subsequently, fasteners may be inserted through the fastener holes and the openings on the housing extensions to couple the EGR tube assembly with the EGR pot housing on the intake.
If the EGR tube assembly is positioned correctly with respect to the EGR port housing, the alignment tabs guide the EGR tube assembly such that the fastener holes on the flange of the assembly align with the openings on the housing extensions. Once aligned, the EGR tube assembly may be coupled with the EGR port housing. However, if the EGR tube assembly is incorrectly positioned (e.g., rotated 180 degrees), the alignment tabs prevent alignment of the fastener holes and the openings. As a result, it may not be possible to insert the fastener through the fastener holes and housing extensions. Consequently, incorrect installation of the EGR tube assembly is prevented. Further, when positioned correctly, by using the alignment tabs, the fastener holes and the openings may be aligned with reduced adjustments. Furthermore, by using the alignment tabs for EGR assembly installation, mis-alignment is reduced as the alignment tabs greatly reduce the potential number of mis-aligned positions. In this way, by guiding alignment of the EGR tube assembly with the EGR port housing, and by providing directional guidance for positioning of the EGR tube assembly with the EGR port housing, the alignment tabs reduce time to assemble the EGR tube assembly. Furthermore, by ensuring proper alignment, improper coupling between the EGR tube assembly and the EGR port housing is reduced. As a result, proper sealing between the EGR tube and the intake is maintained during the vehicle lifecycle.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.